Reassortant swine influenza viruses isolated in Japan contain genes from pandemic A(H1N1) 2009

• Published in: Microbiology and immunology Vol. 58; no. 6; p. 327
• Main Authors: Kanehira, Katsushi, Takemae, Nobuhiro, Uchida, Yuko, Hikono, Hirokazu, Saito, Takehiko
• Format: Journal Article
• Language: English
• Published: Australia 01.06.2014
• Subjects: Animals; Antibodies, Viral - immunology; Cluster Analysis; Humans; Influenza A Virus, H1N1 Subtype - genetics; Influenza A Virus, H1N2 Subtype - genetics; Influenza A Virus, H1N2 Subtype - isolation & purification; Influenza A Virus, H3N2 Subtype - genetics; Influenza A Virus, H3N2 Subtype - isolation & purification; Japan; Molecular Sequence Data; Orthomyxoviridae; Orthomyxoviridae Infections - veterinary; Orthomyxoviridae Infections - virology; Phylogeny; Reassortant Viruses - genetics; Reassortant Viruses - isolation & purification; Recombination, Genetic; RNA, Viral - genetics; Sequence Analysis, DNA; Swine; Swine Diseases - virology; Viral Proteins - genetics; Japan; swine influenza virus; pandemic A(H1N1) 2009; reassortant influenza virus
• ISSN: 1348-0421
• DOI: 10.1111/1348-0421.12152

In 2013, three reassortant swine influenza viruses (SIVs)-two H1N2 and one H3N2-were isolated from symptomatic pigs in Japan; each contained genes from the pandemic A(H1N1) 2009 virus and endemic SIVs. Phylogenetic analysis revealed that the two H1N2 viruses, A/swine/Gunma/1/2013 and A/swine/Ibaraki/1/2013, were reassortants that contain genes from the following three distinct lineages: (i) H1 and nucleoprotein (NP) genes derived from a classical swine H1 HA lineage uniquely circulating among Japanese SIVs; (ii) neuraminidase (NA) genes from human-like H1N2 swine viruses; and (iii) other genes from pandemic A(H1N1) 2009 viruses. The H3N2 virus, A/swine/Miyazaki/2/2013, comprised genes from two sources: (i) hemagglutinin (HA) and NA genes derived from human and human-like H3N2 swine viruses and (ii) other genes from pandemic A(H1N1) 2009 viruses. Phylogenetic analysis also indicated that each of the reassortants may have arisen independently in Japanese pigs. A/swine/Miyazaki/2/2013 were found to have strong antigenic reactivities with antisera generated for some seasonal human-lineage viruses isolated during or before 2003, whereas A/swine/Miyazaki/2/2013 reactivities with antisera against viruses isolated after 2004 were clearly weaker. In addition, antisera against some strains of seasonal human-lineage H1 viruses did not react with either A/swine/Gunma/1/2013 or A/swine/Ibaraki/1/2013. These findings indicate that emergence and spread of these reassortant SIVs is a potential public health risk.